CHICAGO -- Now is the time for the Pirates to take care of business -- at least if they can muster the energy to wake up.

The Pirates defeated the Cubs, 3-0, at Wrigley Field in a game that didn't begin until 10:42 p.m. CT on Monday. Now they leave Chicago and begin a key three-game series on Tuesday night at PNC Park with the Brewers, with whom Pittsburgh is tied in the National League Wild Card standings.

Both teams are 2 1/2 games behind the Cardinals for the second spot, while the Dodgers sit a game behind the Redbirds.

The Phillies, 3 1/2 games back of St. Louis, and D-backs (4 1/2) remain close behind Pittsburgh and Milwaukee.

Wells Fargo

Tuesday's key games to watch (all times ET)

Dodgers (Harang, 9-9) at Nationals (Zimmermann, 10-8), 7:05 p.m. Preview >

Brewers (Gallardo, 15-8) at Pirates (Burnett, 15-7), 7:05 p.m. Preview >

Astros (Abad, 0-4) at Cardinals (Lohse, 14-3), 8:15 p.m. Preview >

If the postseason started today ...

This is how the teams would match up: Postseason Bracket »

Postseason 101

Magic numbers
To calculate a team's magic number, take the number of games it has remaining and add one. Then subtract the difference in the number of losses between that team and its closest pursuer.

Tiebreaker scenarios
A tiebreaker game will be played to determine a division winner, even if the tied clubs are assured of participating in the postseason. If a division championship tiebreaker is necessary, the head-to-head record between the clubs will determine home-field advantage. If the head-to-head record is tied, then the division record will be the next tiebreaker.

If two clubs are tied for the two Wild Card berths, home-field advantage will be determined by the head-to-head record between the clubs. If the head-to-head record is tied, then the division record will be the next tiebreaker.

Tiebreaker rules »

2012 postseason schedule
Wild Card playoff games: Oct. 5
Division Series: Oct. 6-12
AL Championship Series: Oct. 13-21
NL Championship Series: Oct. 14-22
World Series: Oct. 24-Nov. 1